How do you measure flow in a pipeline? The simplest
way is integrated, saddle-mounted propeller or magnetic meters. For example, see the post on McCrometer magnetic flow meters: https://allwaterrights.com/tag/inline-magnetic-flow-meter/. Propeller meters look much the same. Both mount through a hole cut in the pipeline, making them quick to install, and easy to remove for maintenance. These meters can handle some sediment and still be accurate, although water with a lot of silt and sand wears out propellers faster.
What about cost? For integrated meters, the costs start at about $3,200 delivered, and go up with diameter.
If you want to spend the least amount of money and still have accurate flow
measurement, a paddlewheel meter may be a good solution. These can be integrated, or can be assembled from the meter, data collector,
display, and possibly other parts.
For an idea of the cost, an IP 800 paddlewheel meter, FT450 display, and DL76 data collector for a small pipeline cost about $2,000 delivered.
That is about $1,200 cheaper than a magnetic meter for the same-sized pipeline.
So, why not always use a paddlewheel meter rather than more expensive magnetic or propeller meters? Paddlewheels wear out faster if there is sediment in the pipeline. I have seen installations where pumping from a muddy river wore out a paddlewheel
in a year, but a propeller meter lasted 3 years pumping from the same river before needing refurbishment. The shaft and wheel can be replaced in the field, at a lower cost than propeller or magnetic meter refurbishment. However, busy farmers and ranchers don’t have time to check the paddlewheel once or twice a year, so the meter installation is at a greater risk of losing data than a propeller or magnetic meter.
If you are brave or experienced enough, you could get a paddlewheel integrated with the data collector, and no external display. This would get your delivered cost down to about $1,500. Data needs to be downloaded more often, perhaps every 2 to 3 months, to ensure the meter is working correctly. Also, the meter needs to be installed from the side, not the top, so more clearance is required to the side.